Model Selection

SNAP evaluates, chooses, and downscales the best performing models for the North

A Global Climate Model (GCM) focuses on projections of climate change by simulating how Earth’s physical processes respond to increasing greenhouse gas concentrations. Over 20 global climate modeling centers produce more than 60 GCM versions, all attempting to approximate the global climate.

We use a methodical, statistically based protocol to assess which GCMs best replicate historical climate patterns in Alaska and the Arctic so that we can provide the best models and data for our subregion of the globe.

Model evaluation

SNAP evaluated the performance of 15 GCMs used in the Coupled Model Intercomparison Project 3 (CMIP3) and 22 GCMs used in the Coupled Model Intercomparison Project 5 (CMIP5). For several regions across Alaska and the Arctic, we calculated the degree to which each model’s output aligned with 1958–2001 climate data for precipitation, sea level pressure, and surface air temperature.

Model evaluation results

The AR5 model evaluation is described in Downscaling of climate model output for Alaskan stakeholders (Walsh et al. 2018).

  • Focus: Alaska and the Arctic
  • Evaluates historical climate model runs over several geographic domains
  • GCM performance is ranked based on minimum error with respect to a European Re-Analysis (ERA-40) baseline data set using several error metrics
Project Center Model Acronym
CMIP3/AR4 Canadian Centre for Climate Modelling and Analysis General Circulation Model version 3.1 - t47 CCCMA-CGCM3.1(T47)
CMIP3/AR4 Max Planck Institute for Meteorology European Centre Hamburg Model 5 MPI-ECHAM5/MPI-OM
CMIP3/AR4 Geophysical Fluid Dynamics Laboratory Coupled Climate Model 2.1 GFDL-CM2.1
CMIP3/AR4 UK Met Office - Hadley Centre Coupled Model 3.0 UKMO-HadCM3
CMIP3/AR4 Center for Climate System Research Model for Interdisciplinary Research on Climate JAMSTEC-MIROC3.2(medres)
CMIP3/AR4 5-model average Calculated as the mean of the above 5 models 5modelavg
CMIP5/AR5 National Center for Atmospheric Research Community Earth System Model 4 NCAR-CCSM4
CMIP5/AR5 NOAA Geophysical Fluid Dynamics Laboratory Coupled Model 3.0 GFDL-CM3
CMIP5/AR5 NASA Goddard Institute for Space Studies ModelE/Russell GISS-E2-R
CMIP5/AR5 Institut Pierre-Simon Laplace IPSL Coupled Model v5A IPSL-CM5A-LR
CMIP5/AR5 Meteorological Research Institute Coupled General Circulation Model v3.0 MRI-CGCM3
CMIP5/AR5 5-model average Calculated as the mean of the above 5 models 5modelavg

We acknowledge the World Climate Research Programme’s Working Group on Coupled Modeling, which is responsible for CMIP, and we thank all the climate modeling groups for producing and making available their model output. For CMIP the US Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and leads development of software infrastructure in partnership with the Global Organization for Earth System Science Portals.

Model selection

Our analysis showed that the best-performing models over the larger domains also tended to be those that performed best over Alaska. We offer:

  • Downscaled projections for each model
  • Downscaled projections for a five-model average